(1) Field of the Invention
The present invention relates to the technical field of the continuous casting of liquid metal, and in particular it relates to a shroud designed to avoid the reoxidation of said metal as it is transferred from an upper metallurgical vessel to a lower metallurgical vessel, and also to a manipulation device for such a shroud.
(2) Description of the Related Art
In the following description, reference will be made more particularly to such a shroud used in the casting of steel between a casting ladle and a tundish, without this being interpreted as a limitation of the present invention.
There is known in the prior art an installation for casting liquid metal, in particular liquid steel, making it possible to transfer the liquid metal from a casting ladle to a tundish, intended to distribute the liquid metal into casting moulds. For the transfer of liquid from the ladle to the tundish, use is generally made of a cylindrical shroud, referred to as a ladle shroud, which is kept pressed against a flow control valve arranged in the bottom wall of the casting ladle.
The flow control valve, referred to as a “sliding gate valve”, is equipped with two superposed plates sliding one with respect to the other so that the valve can assume a closed configuration, during which the casting ladle can be displaced, and an open configuration which allows the liquid to pass so as to be transferred into the tundish. The movement of the valve into the closed configuration or into the open configuration is brought about by drive means, often in the form of a hydraulic jack. In order that they are arranged as close to the valve as possible, the drive means are attached, at the moment when the ladle arrives close to the tundish, to the casting ladle or directly to the valve.
Furthermore, when the casting ladle is brought above the tundish, the ladle shroud is also moved below the valve, holding it against the lower plate or a nozzle, such as a collector nozzle, extending the latter. The operation of holding the ladle shroud against the valve can be performed manually or automatically, with a manipulation device arranged on the floor of the installation.